DA: Loner Son Killed Twin Brother, Parents In Pa.

KING OF PRUSSIA, Pa. (AP) – Prosecutors say a suburban Pennsylvania man charged with brutally killing his twin brother and their parents was an introverted loner with “some aspect of mental illness.’’

Montgomery County District Attorney Risa Ferman said Monday investigators are still trying to determine a motive for the slayings of Joseph and Susan McAndrew and their 23-year-old son, James.

Another son, Joseph Jr., was found covered in blood outside the family’s home in the upscale suburban neighborhood of Upper Merion. Police say he told officers there had been an “extermination’’ at the home.

Officers then discovered the bodies of the three victims on the floor of the kitchen. Authorities suspect they were killed with an 18- inch dagger.

Joseph McAndrew Jr. is being held without bail. It was not clear if he had an attorney.